Investors breathed a sigh of relief last night after the European Central Bank unveiled a third round of bond buying, but economists says it's too early to tell if it will snap the global economy out of its moribund track.

Under the programme, the bank can buy a virtually unlimited amount of bonds from heavily indebted member states to stop those countries' debt costs from spiralling too high.

The aim is to take speculators out of the eurozone debt market by positioning the ECB as a backstop, or buyer of last resort, and give the likes of Italy and Spain enough breathing room to get their fiscal houses in order.

Global markets took the news as a reason to rally, with US and European equities charging towards new multi-year highs.

Growth-linked currencies such as the New Zealand dollar reversed their declining tracks, and yields on Spanish and Italian government bonds eased further.

Yet despite the flurry of activity, economists are split as to whether the move is step towards a long-term solution or another temporary policy boost that will wear off in the sober light of day.

On the cup-half-empty side, ANZ chief economist Cameron Bagrie believes the bond-buying programme doesn't address any of the underlying issues.

"We need to be realistic about this," he said. "This is a country mile away from full blown solution, which would centre on growth (in Europe) and that is still the missing ingredient."

Without economic growth, countries such as Spain can't chip away at their unemployment rate, meaning tax revenues will remain depressed and debt levels are likely to rise as the government foots higher social security costs.

Bagrie is expecting the euphoria from last night's announcement to wear off in the months ahead with the mood "shifting from euphoria to panic".

That's likely to add further headwinds to the New Zealand economy which is reliant on robust offshore demand for its export products.

BNZ market strategist Mike Jones is more hopeful on the outlook, calling it a step away from the cycle of stimulus-and-panic which has driven markets since the global financial crisis.

"It's a game changer, and for a lot of people it's a real silver bullet to dealing with the European debt crisis," he said. "The ECB seems to be doing what is needed to rescue the eurozone."

He believes that by stripping out the pressures from servicing higher debt costs, the troubled euro countries can then tackle the source of the problem: the high levels of debt.

He's expecting that will stabilise some of the volatility in the global economy, albeit on a gradual basis, with New Zealand benefiting indirectly through normalisation of the Chinese and Australian economies - our two biggest trading partners.

A critical difference between this measure and previous ones for Jones is the addition of a stick to the ECB's traditionally carrot-only approach.

The central bank has insisted participating member states signs up to strict fiscal rules, and has reserved the right sell back any debt it buys if they don't comply.

Just which scenario is likely to emerge is too clouded in multiple event risks to accurately say at this stage, according to Deutsche Bank economist Darren Gibbs.

The first of which is whether Italy and Spain accept the ECB's offer to intervene in their bond market, as well as the ongoing German constitutional court challenge to the legality of the bank's rescue fund which will be funding the bond buys.